Method of impregnating porous materials



Patented Oct. 17, 1933 I I e UNITED STATES PATENT OFFICE DIETHOD OF IMPREGNATING POROUS MATERIALS Philip P. Gray, Hollis, N. Y., and Ernest E. Werle, Grantwood, N. J., assignors to The Fibre Conduit Company, Orangeburg, N. Y., a corporation of New York No Drawing. Application November 12, 1930 Serial No. 495,287

2 Claims. (Cl. 91-10) This invention relates to impregnating porous this particular temperature relation, and the material, such as fiber or pulp, with bituminous treatment may start or end with a lower temcompounds'such as asphalt, pitch, and the like perature, or vice versa. The temperatures emior waterproofing, insulating, and similar purployed may range in the case of water gas tar 5 poses. pitch and newsprint pulp from about 300 F. to h More Particularly, t e invention inc1udes a 450 F. and we find that three or four alternations method of treating formed bodies, such as duct or temperature v a period Of as many hours or conduit, made of cellulosic fiber or pulp for the e are Suflieient'to give Substantially the desired purpose of rendering the bodies waterproof, and sult and that longer me 0 m e alternations maintaining their good insulating properties for do not eerresporrdirlgly P QVe the p e electrical wiring underground, or in the floors or The temperature llmltS may V 11 y V y m ll of buildings or in t open n; The cordance with the materials employed, for the principles of the invention are, however, applireason that different fiber 0r p p can withcable quite broadly to the impregnation of such Stand different temperatures Without jy, and materials or objects regardless of the use to which dlfierent impregnatmg Substances W111 have t are t be put different melting points and viscosities. Further- The impregnating substances which we have 'more, many of the impregnating compounds or employed and as to which the invention is mixtures have volatile components, so that the particularly pertinent, are substances such as upper h limit will ,depehd semewhat pitch, which may be of quite varied and even upon the ehhpeshheh of the lmpreghahhg h complex composition or mixture, but which in e fer thlereeseh' h hhal temperature In any case are susceptible of being melted at an the 1mpreghahhg tanks 18.80 eheseh that proper elevated temperature, and on cooling to normal i e of the product wlh e place .Wheh the temperatures will assume a substantially solid or We 15 remehed m the lmpregmtmg tank approximately nomfiuid state This is of particular mportance n the manu- Forthe purpose of clear illustration, but withfeeture h fiber eehdutlt and e m t out limiting the invention thereto, we shall refer the extener W111 not retem eh ebleeheh" to the treatment of fiber conduit or duct made of able thlekhese of plteh ever; the pulp wood pulp or newsprint pulp with pitch, such as T examples reshlts e for example, that known in the trade as water tamed m h newsprint pulp homes i gas tar pitc Such duct is usually molded of gas tar plteh h accordance wlth the the pulp into cylindrical lengths or sections vehhoh ahd by the erdlhary method which are dried and then impregnated with the water gas tar pitch, or the like, at a temperature Water above the melting point of the pitch but below Percent p- 5 the charring temperature of the pulp. tfg Our invention resides in an impregnating 37C. process in which an alternation df temperature or a plurality of temperature cycles are employed, schan eHghrsAso-atojr. Not transferred- 80% 2% 40 which we find results in a marked increase in the fi ggfi g g gf iigm 3:333}; 3%: 9o

waterproofing effect. To a certain extent there is also an increased absorption of the pitch, al- W though this increase in pitch absorption is not The above figures show plainly the greater abin itself sufficient to account for the substantial sorption of the pitch and'the greatly improved 5 increase inthe waterproofing efiect. waterproofing obtained bythe alternation of 95 The alternation or cycle of temperature in the temperature as compared with treatment at a impregnating operation is preferably one in which uniform temperature for approximately the same initial and final temperatures are higher than one time. The articles treated in these examples or more of the intermediate temperatures of were left in the tank while the temperature treatment, but good results are not dependent on changes were being effected. 100

Water absorption 120 changes It might ordinarily be supposed that increasing temperature would represent a decreased weight percentage of pitch saturation, due to the lower density of the pitch at the elevated temperature, and that the lower temperature alone would therefore represent the greatest weight percentage of pitch absorbed. The above figures, however, show that the relation is complex in that the percentage of pitch saturation'decreases steadily with increases in temperature under the uniform temperature treatment, whereas the alternating temperature treatment gives a percentage of saturation almost equivalent to the saturation obtained at the lowest uniform temperature treatment. 'The waterproofing quality is shown to be much greater in the alternating temperature treatment than that @obtained at the lo ft uniform. temperature treatment, although the latter represented a greater percentage of absorption of the pitch. The results indicate that increasing temperature alone in the uniform temperature treatment tends to decrease the amount of pitch absorption, although it may improve the waterproofing quality. The alternating treatment does not substantially reduce the weight percentage of The following table represents results obtained portion to slight increases in the saturation.

The fact that the principal gain, as compared with the ordinary method of impregnation, is obtained in a relatively few cycles of temperature changes, after which the slight additional gain may not be commercially economical, is shown by tests in which samples were treated for 4 hours total time between temperatures of 300 F. and 400 F., with a like period of time at each of the temperatures stated, namely, 300 F. then 400 F., showing in the treated sample a water absorption of 13.5%, 400 F. then 300 F. then 400 F., showing in the sample treated a water absorption of 6.1%, and treatment at 400 F. then 300 F. then 400 F. then 300 F. and finally 400 F., showing in the treated sample a water absorption of 5%.

we claim:

1. The method of impregnating a porous body which comprises the immersion treatment of the body with an impregnating material for substantial time periods first at one temperature, then at another temperature, and again at the first temperature, each of said temperatures being above the melting point of the impregnating material.

2. The method of impregnating a porous body which comprises the immersion treatment of the body with an impregnating material at one temperature, continuing the treatment at a lower temperature, and repeating the treatment at a higher temperature, each of said treatments being for a substantial time period and at a temperature abovethe melting point of the impregnating material.

' PHILIP P. GRAY. ERNEST E. WERLE.

on impregnating newsprint pulp duct with various substances under specified conditions, the

at 350 F., in each test.

Water-absorption Satura- 37 0. 1 37 0. month 37 0.6

120 hrs. immermonths sion Pitch Maintained uniformly at 3:50 F.4hours 66-68% 13.0% 20.0% 30.6% Alternating 300-450 F. 4 chan es 4 hours (not transierr 70-73% 1.5% 3.5% 13% Sia'nolite (an asphaltic maten'al) Maintained uniiormly at 350 F.4hours'. 66-70% 10.0% 17.7% 26.6% Alternating 300450F."4

.chan es 4 hours (not transnu- 6 8 5% 4.1% 6.2% 12.1% .Stanolite-l-minq amounts of was tailing: up to 6% Maintained uniiormly at i 350 13 41mm! 65-68% 711% 1219% N-84% term In this case no greater saturation obtained. 

